A New Glass for a New Era: Borosilicate Glass

By Corning Museum of Glass

People have shaped and molded glass for millennia, and experimented with improving the basic recipe for glass. But it took innovations in modern chemistry to make a new glass for a new era possible. 

Portrait Inlay of Pharaoh Akhenaten (-17) by UnknownCorning Museum of Glass

Glass has shaped human culture for 3,500 years. Common sodalime glass is made from soda ash (sodium carbonate) and lime (calcium carbonate).

With the rise of modern chemistry, glassmakers developed new glass formulas to create glasses with new, desirable properties.

Harbor Lantern with Dioptric Lens (1852 - 1866) by Brooklyn Flint Glass Works, ManufacturerCorning Museum of Glass

The need for a better glass

In the 1800s, as railroads grew in complexity, signal lanterns became an essential part of transportation safety. But, sodalime glass expands when heated, and shrinks when it cools. The combination of hot oil lanterns and cold weather caused lantern lenses to break (thermal shock), resulting in costly accidents.

Engraving of Jenaer Glaswerk in 1900 (1902) by Jenaer Glaswerk Schott & Gen.Original Source: View Original

Through careful experimentation, German glassmaker Otto Schott (1851-1935) discovered that adding boron to glass recipes produced a borosilicate glass resistant to thermal expansion.

Product Information: Technical data on Corning's #7740 glass (1963-06-19) by Corning Glass WorksCorning Museum of Glass

Only in the past few years have scientists learned why adding boron makes glass expand and contract less than sodalime under changing temperatures.

In sodalime glass, sodium atoms soften the glass, making it easier to shape. But sodium also makes glass expand when it heats up. When sodium atoms are hot, they vibrate and expand more than most other atoms in glass.

In borosilicate glass, softening is done by the added boron atoms, so less sodium is needed. As a result, borosilicate glass expands only one-third as much as sodalime glass.

Engraved Pyrex Teapot with Lid and Underplate (1929/1935) by Corning Glass WorksCorning Museum of Glass


The original Pyrex glass is a borosilicate glass. The main chemical elements are silicon, oxygen, sodium, aluminum, and boron. You may be more familiar with boron than you think - it’s an essential component of the laundry additive borax! Borosilicate glass expands and contracts less than sodalime glass when heated or cooled, making it less likely to break as it heats up quickly in an oven or on a Bunsen burner in a lab, or as it cools down on a countertop.

Lenses, roundels and slides for railroad & traffic signals (1926) by Corning Glass Works, Railroad and Marine DivisionCorning Museum of Glass

In Corning, NY, scientists Eugene Sullivan (1872-1962) and William Taylor (1886-1958) developed a new borosilicate formula. This borosilicate glass, called Nonex for “non-expansion” glass, performed well as railroad lenses.

Bessie and Jesse Littleton, 1910, From the collection of: Corning Museum of Glass
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In 1913 Corning Glass Works engineer Jesse Littleton (1888-1966) was looking for other uses for Nonex glass at the same time that his wife Bessie (1886-1966) was surveying another broken ceramic casserole dish in her oven. Jesse wondered if Nonex would work better.

Pyrex Battery Jar (1950/1970) by Corning Glass Works, ManufacturerCorning Museum of Glass

Using a sawed off borosilicate glass battery jar like this one, Bessie baked a perfect sponge cake for Jessie to share with his co-workers.

Pyrex Baking Dishes (1915/1919) by Corning Glass Works, ManufacturerCorning Museum of Glass

Bessie Littleton’s kitchen experiment led to another variation in the recipe for borosilicate glass. The new glass became known as Pyrex, and was shaped into glass baking dishes.

Bake her a Christmas present in a "Pyrex" dish (1933) by Corning Glass WorksCorning Museum of Glass

An effective marketing campaign made Pyrex a household brand. By 1919, over 4 million Pyrex dishes in about 100 shapes and sizes filled American kitchens.

Warning signals in the line of vision (1927) by Moto Meter Company, Inc.Corning Museum of Glass


In the 1920s, more and more American homes also included an automobile. A thermometer mounted on the radiator cap could alert the driver if their motor was overheating. These thermometers were made with borosilicate glass to prevent breakage from large changes in  temperature.

Corning Glass Works Clinical Thermometer Tubing Ad (1938) by Corning Glass WorksCorning Museum of Glass

The thermometer also became part of the modern household first aid kit. Monitoring the family’s personal health safely and accurately became possible with a borosilicate glass thermometer that wouldn’t easily break.

Corning Little Joe Tube Tower - Tin Pan Time Machine Project (2016) by The Corning Museum of GlassCorning Museum of Glass

For decades, Corning Glass Works produced borosilicate glass thermometers using an ingenious updraw method observed in England by Arthur Houghton, grandson of the founder of Corning Glass Works.

Pyrex Liquid Measuring Cup (1926) by Corning Glass WorksCorning Museum of Glass


Dr. Lucy Maltby (1900-1984), equipped with a doctorate in the newly minted field of home economics, built a test kitchen at Corning. At the test kitchen, researchers tried out new products, reviewed customer feedback and suggested future innovations. Borosilicate saucepans, coffee percolators, and measuring cups emerged from Dr. Maltby’s efforts.

#508 measuring cup (1976-11-16) by Corning Glass WorksCorning Museum of Glass

Continued efforts at innovation led to changes of the Pyrex measuring cup, including its handle.

Pyrex ware presents new measuring cups and mix 'n' measure batter bowl (1983) by Corning Glass WorksCorning Museum of Glass

Further testing and user feedback produced a radical new design: a handle attached only at the top, allowing the measuring cups to stack.

Pyrex laboratory glassware (1931) by Corning Glass Works, Laboratory and Pharmaceutical DivisionCorning Museum of Glass


Borosilicate became the “go to” glass for labware and chemical processing. Its extraordinary durability allowed engineers to design efficient processes without the downtime needed to clean up and replace broken glass.

Organic Chemistry Kit with Original Case (1970/1989) by Corning Inc., ManufacturerCorning Museum of Glass

Borosilicate laboratory glassware like Pyrex (and Duran in Europe) withstands thermal shock, and it is more chemically resistant than sodalime glass, making it ideal for a wide variety of chemical uses.

Worker strips the ladle to remove excess glass (1934)Corning Museum of Glass

The 200-inch Disk

Borosilicate glass was perfect for an out of this world object: the largest telescope ever made!

200-inch Disk (1934) by Corning Glass WorksCorning Museum of Glass

This 20-ton, 200-inch (5-meter) disk is one of the world's largest pieces of cast glass. It was to serve as the gigantic mirror for the Hale telescope on Mount Palomar near San Diego.

In 1934, the first attempt to make the mirror failed when the casting mold broke, but the second attempt succeeded, inspiring future engineers and artists.

200-Inch Disk (2011) by The Corning Museum of GlassCorning Museum of Glass

Worker strips the ladle to remove excess glass (1934)Corning Museum of Glass

Two crews spent 6 hours pouring over 100 ladles of hot borosilicate glass into the improved mold. After 10 months of cooling in an annealing oven, the disk was ready.

Slide of workmen standing in front of 200" disk with one man inside center of disk (1935)Corning Museum of Glass

The disk traveled to California on a whistlestop tour. After arriving at Mt. Palomar, the surface was ground into shape, polished, and coated with aluminum.

The finished mirror became a key part of the most powerful telescope yet, seeing first light in 1949.

Eat Your Hat (1985) by Ginny RuffnerCorning Museum of Glass

Flameworking with borosilicate glass

Although artists have used flameworking (or lampworking) for centuries, the properties of borosilicate glass allowed them to create larger-scale and more complex works. Sodalime glass used by artists must be kept at uniform temperatures or it will crack and break. This limits the scale and complexity of a sculpture. Borosilicate glass enables artists to connect multiple components into large and intricate compositional works with greater ease.

Marie Antoinette Sacrifices the Heart of the Nobility on the Altar of the French Republic (1790 - 1790) by Haly, Pierre, MakerCorning Museum of Glass

Until the invention of borosilicate glasses, flameworkers were restricted to using sodalime glasses.

This scene depicting Marie Antoinette is constructed from several small-scale flameworked sculptures of sodalime glass that have been attached with animal glue. Melting the elements together or making them much larger would have risked breakage due to thermal shock.

Blaschka Nr. 216 (1885) by Leopold BlaschkaCorning Museum of Glass

Craftsmanship in flameworking reached a high point with the biological models of Leopold (1822-1895) and Rudolf (1857-1939) Blaschka. Their brilliant works constructed of finely detailed flameworked sodalime glass elements, were attached with adhesives to avoid the risks of thermal shock.

Woven Heaven Tangled Earth (1999 - 1999) by Plum, Susan (American, b. 1944), ArtistCorning Museum of Glass

Contemporary Art made with borosilicate glass

Working with a hand torch from the inside out, Susan Plum (1944-) used borosilicate glass to construct this complex sculpture inspired by Mayan cosmological traditions. More sensitive to thermal shock, sodalime glass may have been prohibitively difficult to work for such an interconnected object.

Lišková Anthem of Joy in GlassCorning Museum of Glass

In the late 1960s, Věra Lišková (1924-1979) was one of the first artists to use borosilicate glass to create larger-scale sculptures. Inspired by the form of musical notes, her sculpture Anthem of Joy visually communicates the emotion and energy of harmonious sound.

Family Matter (2002 - 2002) by Reynolds, Jill (American, b. 1956), ArtistCorning Museum of Glass

Jill Reynolds (1955-) uses borosilicate glass because it is more amenable than most other glasses to being interconnected. Letters, made of small glass rods and larger tubes filled with a blood-like red liquid, stand in for the models of proteins created during DNA replication.

Smallpox Virus and HIV (Human Immunodeficiency Virus) (2010 - 2010) by Jerram, Luke (British, b. 1974), ArtistCorning Museum of Glass

Luke Jerram (1974-) explores the tension between the beauty of his glass sculptures, the deadly viruses that they represent, and the global impact caused by these diseases. Borosilicate glass is the ideal choice for such sculptures because its resistance to thermal shock more readily allows for such complex constructions.

Eat Your Hat (1985) by Ginny RuffnerCorning Museum of Glass

Ginny Ruffner (1952-) adapted her knowledge of harder, borosilicate glasses, commonly used in scientific glassmaking, to art. Its tolerance for extreme temperature variance enabled Ruffner to create larger compositional sculptures with many separate elements interconnected.

Cross-fire series (2015) by Geoffrey MannCorning Museum of Glass

To give the impression of sound waves flowing through the glass, Geoffrey Mann (1980-) has taken advantage of the unique ability of borosilicate glass to be heated and manipulated in one local area while the rest of the object can be left rigid at much cooler temperatures. Initially formed into clean, symmetrical vessels, the objects in this series were distorted by selectively heating and softening certain areas to achieve the impression of movement.

Corning Museum of Glass - Innovation Center (2018-11-10) by Chris WaltersCorning Museum of Glass

Explore Glass

At the Corning Museum of Glass Innovation Center, you can meet the inventors whose ideas changed the world. Discover how their hard-won insights, their hard work, or sometimes a lucky accident gave us the glass we take for granted.

Credits: Story

Borosilicate Glass Exhibition Team:
Marv Bolt, Curator of Science and Technology
Jane Cook, Chief Scientist
Jim Galbraith, Chief Librarian
Eric Goldschmidt, Flameworking and Properties of Glass Supervisor
Mandy Kritzeck, Digital Media Producer/Project Manager
Richard Urban, Digital Asset Manager and Strategist
Kris Wetterlund, Director of Education and Interpretation
Kathryn Wieczorek, Science Educator

Credits: All media
The story featured may in some cases have been created by an independent third party and may not always represent the views of the institutions, listed below, who have supplied the content.
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